SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5af46201a0b230925ebf3258e1a08ccf51b470e8e81ccf171ba49eaa341bbef7' 
  AND token = 'bcKfXRJkHVSwQTXAvMOjmtECM5D2JVuE+gL4CoTKlqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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