SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cc27d02b78a5ae1f0e1018ec816a9f2434fb1723806da93bde22749d9a341cca' 
  AND token = 'yyJ69IQzpGGasgxr3F28FLCZECONUpkeiNkJlMAzC0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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