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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2d0e0325482cb62321e68fa2b22749e5fc6fcbaee112060a9f647510d833e0c' 
  AND token = 'OM5NfSR5u8MJfg9LFtlOGa/45mpwIbkkeId2jKuLFnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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