SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb58cb9770a4924471bcaccc7552826d7af481d380916bfeb9ae16dfae367f51' 
  AND token = 'rUjQOQlRVSrqlQq79+QCKDl42Z8GnPJQCwwxG2/q+X0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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