SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e0e78ff66c12dac46e28a26a121ff478b5e91685d4bd4fd237c2f3557f39b05' 
  AND token = 'wdS/VyCQlsZjVrKi48AFjmvMsSMR2x7b4RFJZumDCME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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