SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2774ec131bfd0c17ba755cde65304d645c7c97ac391c1bf84a34f968e7120c5e' 
  AND token = 'zKzkSj1Ver1nf6hqWGs56FjTgJPLgX2fYvS7vxl2RiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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