SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a974d4777429388e1d7876bcdb51b2c39d5222ee9040e192247bbfaaa5bf5df' 
  AND token = '2mTdLDBJfNn8MMyrBZTSdGZszS5ANBIZolPh+PL4uYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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