SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c7fb0835c6c5d445291735995f2cea7e1af597591a4a46638a8fd583debf240' 
  AND token = 'K40F9131ZX8PCw37hkmXZYA2J7BIi+Fo7HTLAvlws3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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