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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391939d7b8d8e86e9bbcf9dbbaffe2df6c9d26f924166ef4d4d3c27deac04e42' 
  AND token = 'PX01AGP8qol3WtETz2xibdlO88NJipiJesdnDFrhpT8=' 
  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"
    }
  }
}