SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a200b7815f0a8c4a83da3f6aafb40a8557b33f445086a7201c642ff614bd062f' 
  AND token = 'PJb32ROJOhA17AZGhmIIlnkuQjwDatnk1i374t/u0KI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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