SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ee271a2746c4101528b66b66a4887a5f313b3cdfc09e3989bbcbf85f51ecd50' 
  AND token = '95My4VBm1v+hBXUqYiisUIXArlVHjXZvThJDHYr2XBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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