SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83fbf583e71f97ec77a293451ea9531b3c6baca4e1238f7434687970848c431b' 
  AND token = 'R+4poaBGakNXoEk/Vow7MA5CPU2nChpaEe556FozoOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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