SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30c71dd55308192eba156d22ad8a08a75a755825a990af2262cc44c8077d19e9' 
  AND token = 'Hj2TtyUVaq9Iu9DUKbe/uWVaji3wx0mEWx6GsaI+z90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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