SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab0c8d7876280fe02dd04aa39a44d113b8db437991067348c5995808ba99c429' 
  AND token = 'mpgQHVAdrELWymZ2VuoTkJrbUtxkKiF10rS9YooL1bE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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