SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87b62507ea88dfc748fffe37b5b1171dcd3d2eea8fe31acd54132246fa142f42' 
  AND token = 'mWDD5IsHiaCq+TVZ7sc6r8Crin491ZdN66bxfdD78Pk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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