SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b80e8b710d7bb1b6bcc0d5804258666de1955fd408423854cad8c65755d13fa' 
  AND token = 'kIXvfLMsTAwl4myXmKRBKLbyuaA9chVCC1wLs5ZUHyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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