SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '753b3d1a1d204f3098e4625a697b310a1c7a8a1ed00298ae75ed8a2a284950d1' 
  AND token = '/8MZ7+zhy+rGCJdypKcBAwpFP+bK4on9JfYhS4nuI3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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