SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75d922669a8dbcae7d723680da0f09f29a99db38d30869406b41701eb28020df' 
  AND token = 'UCvvIFPE5JHJ5erMmxVbjDzjUm6ZmjXg5Qz0wjvtWWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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