SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b548caba62d1ccaa21c67746aa5d933a61916897bbbf152da58e11cd34ce13d2' 
  AND token = 'YoujJqhj/QMzs8PfRUP2kTZgiuFXsEDzqUwbHqJJlkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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