SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53290d250ba647520ffdac5b9297212886cf23148701a99cebc7fa6c9354138d' 
  AND token = 'qbajQmvdiR7nOxEaLFiyTGWUJBqJoe6AMTmmrcQwIq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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