SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fbf89a2169727e7330c9d0fa05a73c76ff5879734963afb61637844286c1951' 
  AND token = '4eKHFyxO9g3wFAJtIr9XnXV2Lm+JweNIX9QYSFLTICw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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