SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '408fd99603ccf35240797b9fc0de61abb9e667381c03f6e78fed804c5bc1f267' 
  AND token = 'L3IP9WPbwzJdqABq/SWqRW8m8jMnkVX1ZvqS+sK+oDU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}