SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15fbe0b8e9246a23f2548bce7fa75903858927cfe33452d010fae5daf3acc85e' 
  AND token = 'TupS+lCA0n+vKF+fxy2D4MhzRB7wZLp7pNNmYql+9og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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