SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '730dac991df0272575d10f9d497b7f348520d21ac2b0a43022836aa06f91b674' 
  AND token = '7HuwblFUoInDgvPIHRZceUzmhtm7QFS8cv9QAcgz+vE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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