SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e27f61f9bc90d514aa839a47d833e6a6b646d7ea523c8883df6ad435bc9332c' 
  AND token = 'I4sdK4jL/vrMInY49XJVhccCZgWBcVTzIkTiQSZIonE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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