SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0fce62faa5ec39c9aa98ef2cdb98f1d90b80d1ec3a404dff3778170769178d54' 
  AND token = 'SKwpvLceWyw0QdWGPfIDo+/q3NpObpI3eLdcGjZAK5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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