SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90f5900ee784fabc4d6fbae8cfb49fdda67fe81ee526138138c784805618b076' 
  AND token = 'I+jHMIheQ2d2lPQFEy6CnVvARJM6sL9E74MPELwGhpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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