SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5f3c883a22d1416f519caed00757521a25b57dc1a388fa47cbbcc4d51aba24c' 
  AND token = 'yTuSURxQwSxJujT2zV8WCveN1z61hh7l7OogLmRbUH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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