SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5126d45a8b93864639bde6be92c66cc5355dd8286356a9e30fee45f3b734c781' 
  AND token = 'OBRBf+zPaiVMtbd6KRog+k0Gf9hPKe/xfPAGhE09wjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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