SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf6d3cd846e37ef1fef0496a99662a0f5f32a56cc7480795b9bbe03122bd3d29' 
  AND token = '4vF4dH8+jH4ai8i1JrmdjB5NT65cOHk6frBDfGmdrBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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