SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fccef00769842e21175206332d05e68af5846b6ad0f35bef533dbcc12600b2f4' 
  AND token = 'Qp4uiqO7LApY2TNBcNS44euWkXL0IlRdat6RinoejkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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