SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b6a144acfdca7b75cca5fccac7d08644cd6db247fa075d1022c10d8e5461b77' 
  AND token = 'zK1RP2WuRjeTXDR3Pxh2s7BTvpWyyt7AMjV7jTOBEf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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