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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ddf7d3bb4a66f1e097d6c4566042d0a578e3c1e5e6a83fa65ce23dea9a00f37' 
  AND token = '6xTEAll05MmRsrCTFtBZMSRKHvOfBEXE5Ft9cODz1eo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}