SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6148224882aec9140020f3a644056f3be96c25d901342bee08f8603e11952d0' 
  AND token = 'CDVrl1XnEk+9pZwA3S0S5fwrbK/TneL2vZ4plsfD66w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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