SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50fc621e1a3037c521d216d47a0fe408dba9160bfa44a00966e6fbea9e636a8' 
  AND token = 'vtB7utucr+GuIq0QYAvhHEPSaF425Xff6OrIxy9SKeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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