SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6853a0a9602cbfd004adbc4a59728ef5d2d11b48a5b160d1d88c06c09a72788' 
  AND token = 'GXElYp0QzChsL6OQT8ddwE+0xCPz/pLvkKBBT4SJbh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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