SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d40143d63c2be14fe87feec126b4bd1163e4a312d11fb0c78470f9d426f96f' 
  AND token = 'wrHgfFF5NsZDebXxUeRkkhtmccs+On40qfjvsAiJBzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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