SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fb749412a4dbe0e7cdc3a345f0a63afa3d031ee1d8df26835a281a0422bbc89' 
  AND token = '6F3MeRtZPQX63xlrZFQE2OVRqSJ36tN3aKsiYMcFVQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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