SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '703ccc2377e5ef0c0e917b167672b9d2009136193db4df388d9e03dc72ac97cc' 
  AND token = 'jaEwkNwqJEdl+C+sWn4JKchWS7X3IsUNfdMsGEQtsiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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