SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f68084e098f22092ff81b41fd61301ea1cff6e8b757d0b2bee620203049e886' 
  AND token = '2d974ELnSX0yB/+Qo8tQFjBJWXj6eVa/JDbN3bLB3IM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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