SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f66e55b518e331667ba7d5d28a19137d03d3f243829a17acdb5b8f1a489f0a9' 
  AND token = 'scRZZTXogRXJSwwufQ3vsXWxnQAhvLh8veO+TCsQqrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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