SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '63e9b1a7abe21472effcd722151744c33f1bee9a7f9fc7ea370a683d16af5508' 
  AND token = 'FOXB/FQ7Ua713fVw+2YP2aB8ILIgsQUYKylz0v9dCCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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