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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e9dc9d4ff70dff15b1b89aa2ae2ecd53149da991faa227832437c6448d9e4f98' 
  AND token = 'tLYOYjQDbKtFp0iok2wdLw6ag0qgAoaE5Dizeq3sBcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}