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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '688fea0acd8f87bba0f2e52dfd1e73c5403ff139a9a5c3ee1e5bfceb3effa232' 
  AND token = 'EvBiZ1pbsDOd9x6nVjZbqY+K3Db8cPWhAhiUfCvT/kI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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