SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '425a119221451668f2a378cf496a335b034dd6fb5e23fed6d21d66f867cbc2e7' 
  AND token = '7a1JKWD6L3oTf9mcRogGko/zSvwZLZDiHzZmseq14ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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