SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d61c626ddae72d8a01756953ddf838adaa78639a70746163a4b805ca3c732e3' 
  AND token = 'ho7dPW1yDSLCyndTkv9QPQCJydkuKHBevBauNzP/QG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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