SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76c08dcb49d784ac6d7a225c35167f9da095d6548d746fff9e6155fefd197751' 
  AND token = 'rP64Tm9jLVqllElDv98hWLk+nenpH1R1N3/E/obxzSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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