SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d402bdf665fdab75da5f51353ff5ce0984c83427660668d69c44993592d9f90' 
  AND token = '4QPgZWh+eFNwpzw7WXajngB1H6UdJMqIT801ngbqSgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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