SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1645658eeb748943d44eb496165122c233384dd9929e81597e0f8fe4ee0c8def' 
  AND token = 'LJ9dPFddkSOpo2LPYpsXDD3FSdMYY437qq/V7wv5O/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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