SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f76e2d5c6aa888a6c2ebce9ff12b35f6b046061265872716fcffb37d962db833' 
  AND token = 'AmUqaOmM/SYVJs+WpBoDAJ73rG22h+hw2lStHrX1BYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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