SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81a1d10f16aa468588fd1ec6c45df711d7d9aa23956a07960643ceaf182b5b3' 
  AND token = 'Z8oxVRKRCp5qJMbaJQ8CWvDDpQx4VN6R1TSTrMbBqaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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