SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9c14ec160de3a711b2d53cb7f9e52406cbeb34760a9f3e19dd2d1852bac07b87' 
  AND token = '3m5/Z9Qo3uK/Uqr5llfSjvZg/1Gzu5uxWZFXKEaiD+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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