SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8345f32d2186258eac3a93e3f3bf1d7220a3dfc1d23e20cd1d1dc6418fb1cbf' 
  AND token = 'ck21FB/anUHOBloScXPSlqu2lruIzLWrEOWvtd9bPhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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