SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a78fdcd57e6043eb2a7ed7bc1d2cb9f2df2bd63fa3280fcc8ad898d28572758c' 
  AND token = 'Dg/JHFdqL7K75KkcwVYBllokCwxI39mji+WUmnV/Bf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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