SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14ba0728d6902565ce04c981baada32f55cda862d2aeb2924752f401be2ec122' 
  AND token = 'gRxHdQ7dVUapC+tGxN3lfKOGsGSGqstvAetRzFYnfJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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