SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2c9f29ac90a8021d549118377d137806e4dc96f357838128d52650b89db09fc' 
  AND token = 'grqb5AFXaCqhjBJJ5nPnBqS9MOJdILxZqDWYWvtfpPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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