SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8cfdc28441493d47fc92384f5eceb6ddc2931c44f8e6a1459090be132533ee5e' 
  AND token = '/e4Xad0YxJanSKggbvZkV/Oq44XEGgRncSQE8pkXEO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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