SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4faafc0b8e43806d3b61d5e751d58c007b512dcac44bf50cd4891fe53dcc394b' 
  AND token = 'hRc4RgxJCgluCw74xQypr8mwMkk2aD3sEHWF2UDR33I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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