SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7151ed5925a62007cc48ce134e12fff2575ece77cacb371c1d44c398a250e55f' 
  AND token = 'PaNgTrPycjhzMZHYuwyCAqDHhBnxEYRIPgi+LoJU3IE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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