SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9a82608588e7c7b75bbb094afd3ed15a96bc2fe7c7c8e26ed1d73d64022c823' 
  AND token = 'pWdyV+Yb9m2Uhw598RTr4mEOsjQZPhBBQhY5hklovqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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