SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e23f085bd76c7250ce4f5e1c02532ec2151fad5f2ec5a30fa2bc862dd75e85' 
  AND token = 'cpK2VfNogPg+oJ9IeDjLsgAV9ethwaZ1nwaUXSYFR6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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