SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7b6b39bd3afa524606cc2129bec848189663e39a4f24ea55b24cc3d7230b73d' 
  AND token = 'dEq/vntBG85l5yLsPBywLZyI6yunGypCIVjjldiDpmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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