SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c459a7265ef7fd37371ea52f032e16bb3e2e1e715719765d82ee1ffd1043c4a2' 
  AND token = 'b5rheJYv9PrqMecsNgtvUvWPbmTudXO0Up1TUPmnGrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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