SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef79424a3b10fc44526565e731779c823a26db953766412c2964868c4c22ed52' 
  AND token = 'GCoCQQxLFrjlsUzhzsGPMQw1sHBjOjmhEU1WYyBa3oI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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