SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e81273753e7506c66973343f4587925156f754d660b4f842c5cf3f18bdafddf2' 
  AND token = 'U4APSNRk8tkA5hb/mWAznHSxFeYB24dwQuFoppYDbzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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