SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b296bd375bf964c98a583322bdb16f70d74e1252f609c50021b053cac1980e1e' 
  AND token = 'wm31GoGa0jOenPChg9to9Cm3W7Fqi8k5N1VutpWLgRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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