SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78962d99ba556519b1abfddac6683bbc1ca0b52e0f5e1da206d8b0de5bcd5e8d' 
  AND token = 'n66aRx3RDA1z1iwo8KGj3BNLblnuv4UgrC/rhvyb9gA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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