SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '379578325f080b9833fa7255ea556cd39064574e80d7d2e20eabd4b56ec7584f' 
  AND token = 'w6mNjQL2I4rZTT1RIGOzpNKe+E2Fqk6snC27yV88vVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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